linux-kernel - Re: [PATCH 1/2] dmaengine: pxa_dma: Remove an erroneous BUG_ON() in pxad_free

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <202310081402.A9A8C49@keescook>
Date:   Sun, 8 Oct 2023 14:03:23 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc:     gustavoars@...nel.org, Daniel Mack <daniel@...que.org>,
        Haojian Zhuang <haojian.zhuang@...il.com>,
        Robert Jarzmik <robert.jarzmik@...e.fr>,
        Vinod Koul <vkoul@...nel.org>, linux-hardening@...r.kernel.org,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, dmaengine@...r.kernel.org
Subject: Re: [PATCH 1/2] dmaengine: pxa_dma: Remove an erroneous BUG_ON() in
 pxad_free_desc()

On Sat, Oct 07, 2023 at 01:13:09PM +0200, Christophe JAILLET wrote:
> If pxad_alloc_desc() fails on the first dma_pool_alloc() call, then
> sw_desc->nb_desc is zero.
> In such a case pxad_free_desc() is called and it will BUG_ON().
> 
> Remove this erroneous BUG_ON().

Perhaps it could be changed to a WARN_ON()?

> It is also useless, because if "sw_desc->nb_desc == 0", then, on the first
> iteration of the for loop, i is -1 and the loop will not be executed.
> (both i and sw_desc->nb_desc are 'int')

Agreed.

> 
> Fixes: a57e16cf0333 ("dmaengine: pxa: add pxa dmaengine driver")
> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> ---
>  drivers/dma/pxa_dma.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/dma/pxa_dma.c b/drivers/dma/pxa_dma.c
> index 3c574dc0613b..94cef2905940 100644
> --- a/drivers/dma/pxa_dma.c
> +++ b/drivers/dma/pxa_dma.c
> @@ -722,7 +722,6 @@ static void pxad_free_desc(struct virt_dma_desc *vd)
>  	dma_addr_t dma;
>  	struct pxad_desc_sw *sw_desc = to_pxad_sw_desc(vd);
>  
> -	BUG_ON(sw_desc->nb_desc == 0);
>  	for (i = sw_desc->nb_desc - 1; i >= 0; i--) {
>  		if (i > 0)
>  			dma = sw_desc->hw_desc[i - 1]->ddadr;
> -- 
> 2.34.1
> 

-- 
Kees Cook